1. Field of Invention
The present invention relates to a device protection structure for preventing plasma charging damage and vertical cross talk, and the method of manufacturing such a structure. More particularly, the present invention relates to a device protection structure capable of preventing device damage due to plasma during fabrication as well as vertical cross talk between neighboring metallic layers and the method of manufacturing such a structure.
2. Description of Related Art
Current semiconductor processing relies heavily on plasma operations. Because sufficient energy is transferred to the plasma when ions are accelerated in an intense electric field, bombarding ions have a specific directionality on a target electrode. Hence, plasma is an important element in sputtering and dry etching operations. Therefore, plasma is commonly employed, for example, in plasma-enhanced chemical vapor deposition (PECVD), high-density plasma chemical vapor deposition (HDPCVD), reactive ion etching (RIE) and anisotropic etching.
However, since highly energetic ions are generated in a plasma operation, electric charges produced by the plasma are capable of damaging the semiconductor device structure. Therefore, a diode is normally formed and connected to the metallic line in a circuit layout as shown in FIG. 1. FIG. 1 is a circuit outline showing a conventional protection device for preventing damage due to plasma charging. In FIG. 1, the gate 102 of a MOS field effect transistor 100 is connected to a metal contact 106 by a polysilicon line 104. The metal contact 106 is connected to another metal contact 110 via a metal line 108. The metal contact 110 is in contact with a diode 112. Excessive charges produced in plasma operations are conducted away by the diode 112, via the metal line 108 and other conductive layers. However, after the polysilicon line 104 is formed but before the metal line 108 is connected, there is no conductive pathway to channel away excessive electric charges produced by plasma operations. Consequently, devices may be damaged, which leads to a lowering of product yield.
Furthermore, as shown in FIG. 1, metal line 108 and another metal line 116 are normally connected via a dielectric opening 114. In the conventional processing operation, no specific structures are formed for preventing cross talk between metal lines 108 and 116, or cross talk between multiple conductive lines. Hence, a device is often functionally deficient leading to abnormal operation.
In light of the foregoing, there is a need to provide a device protection structure for reducing damage due to plasma and vertical cross talk between separate metallic lines.